/**
 * Copyright 2009-2020 the original author or authors.
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.ibatis.logging.jdbc;

import org.apache.ibatis.logging.Log;
import org.apache.ibatis.reflection.ExceptionUtil;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashSet;
import java.util.Set;
import java.util.StringJoiner;

/**
 * ResultSet proxy to add logging.
 *
 * @author Clinton Begin
 * @author Eduardo Macarron
 *
 */
public final class ResultSetLogger extends BaseJdbcLogger implements InvocationHandler {

	private static final Set<Integer> BLOB_TYPES = new HashSet<>();

	static {
		BLOB_TYPES.add(Types.BINARY);
		BLOB_TYPES.add(Types.BLOB);
		BLOB_TYPES.add(Types.CLOB);
		BLOB_TYPES.add(Types.LONGNVARCHAR);
		BLOB_TYPES.add(Types.LONGVARBINARY);
		BLOB_TYPES.add(Types.LONGVARCHAR);
		BLOB_TYPES.add(Types.NCLOB);
		BLOB_TYPES.add(Types.VARBINARY);
	}

	private final ResultSet rs;
	private final Set<Integer> blobColumns = new HashSet<>();
	private boolean first = true;
	private int rows;

	private ResultSetLogger(ResultSet rs, Log statementLog, int queryStack) {
		super(statementLog, queryStack);
		this.rs = rs;
	}

	/**
	 * Creates a logging version of a ResultSet.
	 *
	 * @param rs
	 *          the ResultSet to proxy
	 * @param statementLog
	 *          the statement log
	 * @param queryStack
	 *          the query stack
	 * @return the ResultSet with logging
	 */
	public static ResultSet newInstance(ResultSet rs, Log statementLog, int queryStack) {
		InvocationHandler handler = new ResultSetLogger(rs, statementLog, queryStack);
		ClassLoader cl = ResultSet.class.getClassLoader();
		return (ResultSet) Proxy.newProxyInstance(cl, new Class[]{ResultSet.class}, handler);
	}

	@Override
	public Object invoke(Object proxy, Method method, Object[] params) throws Throwable {
		try {
			if (Object.class.equals(method.getDeclaringClass())) {
				return method.invoke(this, params);
			}
			Object o = method.invoke(rs, params);
			if ("next".equals(method.getName())) {
				if ((Boolean) o) {
					rows++;
					if (isTraceEnabled()) {
						ResultSetMetaData rsmd = rs.getMetaData();
						final int columnCount = rsmd.getColumnCount();
						if (first) {
							first = false;
							printColumnHeaders(rsmd, columnCount);
						}
						printColumnValues(columnCount);
					}
				} else {
					debug("     Total: " + rows, false);
				}
			}
			clearColumnInfo();
			return o;
		} catch (Throwable t) {
			throw ExceptionUtil.unwrapThrowable(t);
		}
	}

	private void printColumnHeaders(ResultSetMetaData rsmd, int columnCount) throws SQLException {
		StringJoiner row = new StringJoiner(", ", "   Columns: ", "");
		for (int i = 1; i <= columnCount; i++) {
			if (BLOB_TYPES.contains(rsmd.getColumnType(i))) {
				blobColumns.add(i);
			}
			row.add(rsmd.getColumnLabel(i));
		}
		trace(row.toString(), false);
	}

	private void printColumnValues(int columnCount) {
		StringJoiner row = new StringJoiner(", ", "       Row: ", "");
		for (int i = 1; i <= columnCount; i++) {
			try {
				if (blobColumns.contains(i)) {
					row.add("<<BLOB>>");
				} else {
					row.add(rs.getString(i));
				}
			} catch (SQLException e) {
				// generally can't call getString() on a BLOB column
				row.add("<<Cannot Display>>");
			}
		}
		trace(row.toString(), false);
	}

	/**
	 * Get the wrapped result set.
	 *
	 * @return the resultSet
	 */
	public ResultSet getRs() {
		return rs;
	}

}
